A bipartisan group of US senators have introduced a resolution saying that Saudi Crown Prince Mohammed bin Salman was "complicit" in the murder of journalist Jamal Khashoggi.

The mainly symbolic resolution was introduced on Wednesday and came amid unrest among US lawmakers over President Donald Trump administration's response to the killing of the Washington Post columnist.

Khashoggi, a supporter-turned-critic of the Saudi Crown Prince, went missing on October 2 after entering the kingdom's consulate in Istanbul for collecting documents in order to marry his Turkish fiancée Hatice Cengiz.

After initially saying the journalist had left the consulate alive, weeks later the Saudi administration admitted he was killed there and blamed a "rogue" team.

The resolution said the Senate believed the Saudi Crown Prince "was in control of security forces" during the killing and "based on evidence and analysis made available to this institution, has a high level of confidence that Mohammed bin Salman was complicit in the murder of Jamal Khashoggi", the Hill newspaper reported.

The resolution was non-binding, but if approved, would put the Senate on the record saying the Crown Prince was responsible for Khashoggi's slaying inside the Saudi Consulate in Istanbul in early October.

The resolution also urged the Trump administration and the international community to "hold all parties, including Mohammed bin Salman, involved in the murder of Jamal Khashoggi accountable".

"I believe it's vitally important to US national security interests to make a definitive statement about the brutal murder of an American resident -- Khashoggi -- who has three American citizen children," Graham said in a statement.

The resolution came one day after the Central Intelligence Agency Director briefed senators in a closed-door meeting about the journalist's killing.